Almost all seat belt systems in cars and other motor vehicles made in the past several years have belt retractors that wind up part or all of the belt when it is not in use so that the belt is kept out of the way, rather than lying around and cluttering up the passenger compartment, and is conveniently ready to be put on when needed. The retractor also protects the belt from wear and possible damage when it is not in use.
Although there are belt retractors that are designed to stay loosely in place (not under tension) on the user, it is very common for the winding force to be always present, which means that the belt is pulled fairly firmly against the user's lap or torso or both at all times. The pressure of the belt against the wearer is often bothersome, and there is reason to think that many people prefer not to use seat belts because of the constant pull of the belt against their body.